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|
/*
+----------------------------------------------------------------------+
| PHP version 4.0 |
+----------------------------------------------------------------------+
| Copyright (c) 1997, 1998, 1999, 2000 The PHP Group |
+----------------------------------------------------------------------+
| This source file is subject to version 2.02 of the PHP license, |
| that is bundled with this package in the file LICENSE, and is |
| available at through the world-wide-web at |
| http://www.php.net/license/2_02.txt. |
| If you did not receive a copy of the PHP license and are unable to |
| obtain it through the world-wide-web, please send a note to |
| license@php.net so we can mail you a copy immediately. |
+----------------------------------------------------------------------+
| Author: Hartmut Holzgraefe <hartmut@six.de> |
+----------------------------------------------------------------------+
*/
/* $Id: levenshtein.c,v 1.12 2000/08/21 09:50:52 sas Exp $ */
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
/* #include <unicode/ustring.h> */
/* faster, but obfuscated, all operations have a cost of 1 */
unsigned short int fastest_levdist(const char *s1, const char *s2)
{
char *p1, *p2;
int i, j, n;
int l1 = 0, l2 = 0;
char r[512];
const char *tmp;
/* skip equal start sequence, if any */
while (*s1 == *s2) {
if (!*s1)
break;
s1++;
s2++;
}
/* if we already used up one string, then
the result is the length of the other */
if (*s1 == '\0')
return strlen(s2);
if (*s2 == '\0')
return strlen(s1);
/* length count */
while (*s1++)
l1++;
while (*s2++)
l2++;
/* cut of equal tail sequence, if any */
while (*--s1 == *--s2) {
l1--;
l2--;
}
/* reset pointers, adjust length */
s1 -= l1++;
s2 -= l2++;
/* possible dist to great? */
if (abs(l1 - l2) >= 255)
return -1;
/* swap if l2 longer than l1 */
if (l1 < l2) {
tmp = s1;
s1 = s2;
s2 = tmp;
l1 ^= l2;
l2 ^= l1;
l1 ^= l2;
}
/* fill initial row */
n = 1;
for (i = 0, p1 = r; i < l1; i++, *p1++ = n++, p1++) { /*empty */
}
/* calc. rowwise */
for (j = 1; j < l2; j++) {
/* init pointers and col#0 */
p1 = r + !(j & 1);
p2 = r + (j & 1);
n = *p1 + 1;
*p2++ = n;
p2++;
s2++;
/* foreach column */
for (i = 1; i < l1; i++) {
if (*p1 < n)
n = *p1 + (*(s1 + i) != *(s2)); /* replace cheaper than delete? */
p1++;
if (*++p1 < n)
n = *p1 + 1; /* insert cheaper then replace ? */
*p2++ = n++; /* update field and cost for next col's delete */
p2++;
}
}
/* return result */
return n - 1;
}
unsigned short int weighted_levdist(const char *s1, const char *s2,
const int cost_ins, const int cost_rep,
const int cost_del)
{
int *p1, *p2;
int i, j, n, c;
int l1 = 0, l2 = 0;
int r[512];
const char *tmp;
/* skip equal start sequence, if any */
while (*s1 == *s2) {
if (!*s1)
break;
s1++;
s2++;
}
/* if we already used up one string, then
the result is the length of the other */
if (*s1 == '\0')
return strlen(s2);
if (*s2 == '\0')
return strlen(s1);
/* length count */
while (*s1++)
l1++;
while (*s2++)
l2++;
/* cut of equal tail sequence, if any */
while (*--s1 == *--s2) {
l1--;
l2--;
}
/* reset pointers, adjust length */
s1 -= l1++;
s2 -= l2++;
/* possible dist to great? */
if (abs(l1 - l2) >= 255)
return -1;
/* swap if l2 longer than l1 */
if (l1 < l2) {
tmp = s1;
s1 = s2;
s2 = tmp;
l1 ^= l2;
l2 ^= l1;
l1 ^= l2;
}
if ((l1 == 1) && (l2 == 1)) {
n = cost_del + cost_ins;
return n < cost_rep ? n : cost_rep;
}
/* fill initial row */
n = cost_ins;
for (i = 0, p1 = r; i < l1; i++, *p1++ = n, p1++) {
n += cost_ins;
}
/* calc. rowwise */
for (j = 1; j < l2; j++) {
/* init pointers and col#0 */
p1 = r + !(j & 1);
p2 = r + (j & 1);
n = *p1 + cost_del;
*p2++ = n;
p2++;
s2++;
/* foreach column */
for (i = 1; i < l1; i++) {
c = *p1;
if (*(s1 + i) != *(s2))
c += cost_rep;
if (c < n)
n = c; /* replace cheaper than delete? */
p1++;
c = *++p1 + cost_ins;
if (c < n)
n = c; /* insert cheaper then replace ? */
*p2++ = n; /* update field and cost for next col's delete */
n += cost_del; /* update field and cost for next col's delete */
p2++;
}
}
/* return result */
return n -= cost_del;
}
|
